Joined Nov 2001
17K Posts | 774+
Ely, England
under red alert in the doc i've tried to explain the facts as i know them after 2-hours of checking today.
in none of my parts books ('01, '02, '03, '04, '06) does it mention a new style decomp lobe, or does it mention a better spring.
i've no idea if the decomp was all 're-timed' either.
can anyone throw some light on the subject and while i'm here if you'd like to add to the info that would be great!
this is what i have:
The auto de-compression issue
This was for machines through from '01 to as late as '03. Essentially, the decomp lobe would wear down and not lift the exhaust valve the .040"(1mm) to release some compression while the engine turned under starting. There was also the problem that the lobe return spring would be either weak or unwound which equalled "ineffective". This meant the engine was trying to fight full compression. The partial cure at the time was to add a 'blob' of weld onto the decomp and then re-profile. Husadawg has some great photos
The auto de-comp. bleeds only a fraction of the trapped charge engaging near 85 BTDC and closing near 15 BTDC with a peak valve lift of less than .040". "E" Cranking compression should be roughly 130 PSI. (Lineaweaver)
In '03 Husaberg produced a new camshaft for the 650 and de-comp lobe, they produced another cam for the rest of the range but ommited it from the parts book. The new cam profiles appear to make life easier for the valve train. It's easier to follow by reading through an '04 parts manual than an '03!!!
In '04, everything got new part numbers and a new cam again for the 650.
regards
Taffy
in none of my parts books ('01, '02, '03, '04, '06) does it mention a new style decomp lobe, or does it mention a better spring.
i've no idea if the decomp was all 're-timed' either.
can anyone throw some light on the subject and while i'm here if you'd like to add to the info that would be great!
this is what i have:
The auto de-compression issue
This was for machines through from '01 to as late as '03. Essentially, the decomp lobe would wear down and not lift the exhaust valve the .040"(1mm) to release some compression while the engine turned under starting. There was also the problem that the lobe return spring would be either weak or unwound which equalled "ineffective". This meant the engine was trying to fight full compression. The partial cure at the time was to add a 'blob' of weld onto the decomp and then re-profile. Husadawg has some great photos
The auto de-comp. bleeds only a fraction of the trapped charge engaging near 85 BTDC and closing near 15 BTDC with a peak valve lift of less than .040". "E" Cranking compression should be roughly 130 PSI. (Lineaweaver)
In '03 Husaberg produced a new camshaft for the 650 and de-comp lobe, they produced another cam for the rest of the range but ommited it from the parts book. The new cam profiles appear to make life easier for the valve train. It's easier to follow by reading through an '04 parts manual than an '03!!!
In '04, everything got new part numbers and a new cam again for the 650.
regards
Taffy
